Android: MainActivity is suddenly created again in different Activity without being called? -

i m facing weird behaviour. start new activity b within mainactivity

intent mintent = new intent(this, activityb.class); mintent.setflags(intent.flag_activity_new_task);  //tried addflags startactivity(mintent); 

suddenly (between 10-45seconds), mainactivity starting again, without reason. in logcat, see mainactivity being created again (not resumed), , received intent android.intent.action.main

even more weird is, if start activityc, in same way, it's working fine , not jumping mainactivity...

anyone ideas?

logcat

05-21 15:35:13.897: d/dalvikvm(14312): gc_for_alloc freed 8k, 6% free 18231k/19356k, paused 33ms, total 33ms 05-21 15:35:13.936: d/dalvikvm(14312): gc_concurrent freed 17k, 6% free 18213k/19356k, paused 2ms+5ms, total 33ms 05-21 15:35:14.108: d/dalvikvm(14312): gc_for_alloc freed 71k, 6% free 18235k/19356k, paused 25ms, total 26ms 05-21 15:35:14.123: i/dalvikvm-heap(14312): grow heap (frag case) 27.696mb 10342416-byte allocation 05-21 15:35:14.155: d/dalvikvm(14312): gc_for_alloc freed 0k, 4% free 28335k/29460k, paused 24ms, total 24ms 05-21 15:35:14.178: d/dalvikvm(14312): gc_concurrent freed 1k, 4% free 28334k/29460k, paused 3ms+5ms, total 28ms 05-21 15:35:14.780: i/choreographer(14312): skipped 58 frames!  application may doing work on main thread. 05-21 15:35:23.623: d/dalvikvm(14312): gc_for_alloc freed 5879k, 18% free 28729k/34636k, paused 35ms, total 36ms 05-21 15:36:00.037: d/dalvikvm(14312): gc_concurrent freed 6198k, 18% free 29094k/35320k, paused 7ms+14ms, total 92ms  //above, last result, before mainactivity starting again  05-21 15:37:28.498: i/mainactivity(15078): oncreate() -> android.intent.action.main 05-21 15:37:28.623: d/dalvikvm(15078): gc_for_alloc freed 65k, 2% free 8901k/8996k, paused 44ms, total 45ms 

manifest.xml

    <activity         android:name=".mainactivity"         android:label="@string/app_name"         android:launchmode="singletop"         android:screenorientation="portrait">         <intent-filter>             <action android:name="android.intent.action.main" />             <category android:name="android.intent.category.launcher" />         </intent-filter>           </activity>      <activity android:name=".activityb"         android:label="@string/app_name"         android:launchmode="singletop"         android:screenorientation="portrait">     </activity> 

remove launchmode or add activity, u pushing mainactivity on top of other ones edit: didnt see u did ^^